Receiver and method for receiving a signal

ABSTRACT

A receiver includes a receiver circuit to receive a pulse width encoded signal and a sampling circuit to determine a position of a transition of the pulse of the signal by oversampling the received signal with respect to a quantization function and to generate a signal indicating an unexpected event, when the determined position of the transition deviates from an expected position according to the quantization function by more than a predetermined range, wherein the quantization function maps a plurality of expected positions to a plurality of values.

RELATED APPLICATION

This application claims priority under 35 U.S.C. §119 to German PatentApplication No. 102014115493.2, filed on Oct. 24, 2014, the content ofwhich is incorporated by reference herein in its entirety.

FIELD

Embodiments relate to a receiver and a method for receiving a signal,which may be used, for instance, to receive a datum encoded in a pulsewidth encoded signal.

BACKGROUND

In many fields of technology data are to be transferred in a system fromone location to another. Examples come from all kinds of applicationsand tasks to be performed, for instance, including collectingsensor-related data from a sensor arranged at a different location thanits corresponding control or processing unit responsible, for instance,for collecting and pre-processing the data. Other examples include, forinstance, writing and/or reading data from a memory located at adifferent location, providing control signals to an actuator, readingdata from or providing data to a user interface to name just a fewexamples.

While in many fields of technology and applications, data may betransmitted using highly sophisticated transmission schemes, a tendencyexists to simplify the infrastructure used for transmitting data. Insome of the fields and applications, comparably rough operatingconditions may be present causing, for instance, disturbances in thetransmissions. However, also under these more difficult operationalconditions, the availability of the data may be important or evencrucial for operating the corresponding system.

While highly sophisticated transmission schemes and theirinfrastructures may be capable of operating even under very difficultoperation conditions, the tendency to simplify the infrastructurenecessary to transmit the data is also present in these environments.This may limit the options available to a designer to reduce theinfluence of disturbances onto the signal transmission. Examples ofoptions, which may not be available to a system designer, includeadditional shielding measures, increasing the available computationalpower to allow more elaborate error correcting codes to be used,increasing the signal energy to boost the signal-to-noise ratio andsimilar options.

Nevertheless, a robust operation of such a system, a comparably simplyimplementation and a robust transmission of data may yet be desirable.At the same time, a desire exists to increase the available bandwidthor—in other words—the available data throughput.

In the field of high volume architectures and/or low costimplementations, finding a solution to this challenge may be even morerelevant than in other fields of technology. For instance, in motorizedvehicles communication links via which different components communicatewith one another and transmit data may be subjected to a large varietyof tough operating conditions and a large number of distortions ofdifferent types. Distortions may, for instance, come from electricimpulses used to operate systems of a vehicle, which in turn maycapacitively or inductively couple into the transmission link. Thesituation may further be aggravated by environmental conditions whichmay at least partially lead to a signal degradation or even introduceadditional types of distortions. Among the environmental conditions may,for instance, be large variations of the ambient temperature, theinfluence of moisture and vibrations to name just a few sources ofadditional distortions.

Although in the case of electrical systems and electrical signaltransmission schemes these influences and distortions may be moresignificant than in other transmission schemes, similar challenges mayalso arise using non-electrical signals, for instance, magnetic signals,optical signals or other signals to transmit or exchange data. Moreover,similar challenges may also arise in systems which are not vehicle-basedsystems. Also in other fields of technology, comparable situations mayexist including non-high volume architectures and/or non-low costapplications.

SUMMARY

Therefore, a demand exists to improve a trade-off between the robustnessof a system, in which data are transmitted even under adverseoperational conditions, simplifying such an implementation orarchitecture and the available bandwidth for transmitting data.

This demand may be satisfied by a receiver or a method according to anyof the independent claims.

A receiver comprises a receiver circuit to receive a pulse width encodedsignal and a sampling circuit to determine a position of a transition ofthe pulse of the signal by oversampling the received signal with respectto a quantization function and to generate a signal indicating anunexpected event, when the determined position of the transitiondeviates from an expected position according to the quantizationfunction by more than a predetermined range. The quantization functionmaps a plurality of expected positions to a plurality of values.

It may be possible to improve the previously-mentioned trade-off betweenthe robustness of such a system even under adverse operation conditions,simplifying the implementation and the available bandwidth of theinfrastructure by using a receiver, which verifies as to whether thetransition of a pulse falls into the predetermined range with respect toan expected position or if it deviates from the expected position bymore than the predetermined range. In the latter case the receiverassumes an unexpected event, for instance a distortion interfering witha signal comprising the pulse and the transition. In this case, thesampling circuit of the receiver generates a signal indicating theunexpected event.

Therefore, by employing a comparably simple oversampling technique, itmay be possible to detect unexpected events on the receiver side and toreact in response to the generated signal to the unexpected event. Thismay allow to detect distortions and, therefore, to increase therobustness of the transmission scheme while limiting the impact on thecomplexity of the implementation and the available bandwidth.

Optionally, in a receiver the sampling circuit may be configured todetermine a received value of a plurality of values based on thequantization function and an expected position corresponding to thereceived value, when the determined position of the transition fallswithin the predetermined range around the expected positioncorresponding to the received value. The sampling circuit may thereforebe capable of determining the received value based on the position ofthe transition of the pulse, when the determined position falls withinthe predetermined range around the expected position of the receivedvalue.

The predetermined ranges may be arranged symmetrically around theirrespective expected values or they may be asymmetrically arranged aroundtheir respective expected positions. Hence, the expected positions mayform midpoints of the predetermined ranges or may be located away fromthe respective midpoints of the predetermined ranges.

Additionally or alternatively, the receiver may be configured todisregard a message comprising a received value of the plurality ofvalues, when the sampling circuit has generated the signal indicating anunexpected event. This may allow the receiver or other parts of a systemcomprising the receiver to process messages comprising a received value,which may be disturbed by a distortion or a similar unexpected event. Inother words, the robustness of a system comprising such a receiver maybe increased by discarding messages, in which one or more receivedvalues of the respective message may be faulty due to the occurrence ofan unexpected event.

Additionally or alternatively, the predetermined range may correspond toat the most 30% of a distance between two neighboring expectedpositions. Using a predetermined range of that size may allow on the onehand a reliable determination of unexpected events while a complexity ofthe implementation of the receiver may still be comparably simple on theother hand. For instance, it may be possible to use smaller values forthe predetermined range, for instance, of at the most 20% or even of atthe most 15% or of at most 10%. The smaller the predetermined range iswith respect to the distance between two neighboring expected positions,the more sensitive the receiver becomes with respect to unexpectedevents such as distortions. However, the smaller the predeterminedrange, the more complex the implementation of the receiver may become.

Objects, structures, data, values or the like may be neighboring, whenbetween the respective objects, structures, data or values there is nofurther object, structure, datum or value of the same kind arranged inbetween. Accordingly, two objects, structures, data or values may beadjacent when the two objects, structures, data or values are directneighbors, for instance when they are directly in contact or adjoining.

Additionally or alternatively, in a receiver, the predetermined rangearound the expected position may be given by a predefined number ofsamples according to a sampling time resolution of the receivedoversampled signal. This may allow simplifying the implementation of thereceiver since the predetermined range may be determined by implementinga counter. The predefined number of samples may be fixed, programmableor changeable.

Additionally or alternatively, in a receiver the predetermined rangesfor the expected positions of the plurality of expected positions may beequally sized. This may further allow simplifying an implementation ofthe receiver since variations of the predetermined ranges depending onthe expected positions, the values associated with the expectedpositions or other parameters may be avoided.

Additionally or alternatively, in a receiver the predetermined rangesaround the expected positions are based on a predefined fraction of thevalues corresponding to the expected positions according to thequantization function. This may allow the receiver to determine thepresence of an unexpected event based on the values associated with theexpected positions. The predefined fraction may be equal for some or allpredetermined ranges around the expected positions. The predefinedfractions may be fixed, programmable or changeable.

Additionally or alternatively, in a receiver the distances betweenneighboring expected positions according to the quantization functionmay be equal. This may allow further simplifying an implementation ofthe receiver since the distances between neighboring respectivepositions do not vary and may be constant for all expected positions.For instance, this may allow determining the expected positionindicating the received value with respect to the position of thereceived transition by using a counter and to analyze the counter valuebased on a linear relation.

Additionally or alternatively, in a receiver the quantization functionmay be monotone. For instance, the quantization function may be strictlymonotone. The quantization function may, for instance, map the pluralityof expected positions arranged in an ascending order to the plurality ofvalues arranged in an ascending order. This may also allow simplifyingan implementation of the receiver.

Additionally or alternatively, in a receiver, the quantization functionmay map the plurality of expected positions to a plurality of integervalues. By using integer values it may be possible to further simplifyan implementation of the receiver. Optionally, in such a receiver, amaximum difference between neighboring integer values of a plurality ofinteger values may be equal to one, when the plurality of integer valuesis arranged in an ascending order. This may allow simplifying animplementation of the receiver further. For instance, it may be possibleto disregard one or more of the least significant bits in a digitalcounter implementation or to employ another transformation to map theposition of the received transition to the corresponding received value,depending on the implementation and, for instance, the oversamplingemployed.

Additionally or alternatively, the receiver may be configured to receivethe signal comprising a further transition before the transition,wherein the value is encoded in a time period between the furthertransition and the transition. This may allow a more reliable encodingof the value in the signal.

Optionally, in a receiver, the quantization function may map thedetermined position of the transition to the value by subtracting apredefined offset from the time period between the further transitionand the transition. This may allow simplifying an implementation of thereceiver by implementing a comparably simple subtraction. The predefinedoffset may be fixed, programmable or changeable. The predefined offsetmay be given in any suitable unit, for instance, based on an operatingfrequency of the receiver, the receiver circuit or the sampling circuit,or any time unit derived from the operating frequency of the mentionedcomponents.

Additionally or alternatively, the receiver may be configured to receivethe signal comprising the further transition and the transition astransitions in a common first direction. This may allow a more reliabledetermination of a value encoded in the signal since an asymmetryconcerning a rise time a drop time between the signal levels used forthe transition and the further transition may be of less importance. Dueto the transition and the further transition sharing the same direction,for instance, from a lower signal level to a higher signal level or froma higher signal to a lower signal level, it may be possible to eliminateor at least to reduce effects caused by an asymmetry between the risetime and the drop time of the signal.

Optionally, the receiver may be configured to receive the signal furthercomprising an intermediate transition in an opposite second direction,wherein the intermediate transition is positioned between the furthertransition and the transition. This may further allow improving anaccuracy of the encoding and the decoding of the value comprised in thesignal. For instance, the intermediate transition may be used as atransition from a second signal level to a first signal level, whereinthe transition and the further transition are transitions from the firstsignal level to the second signal level. In other words, theintermediate transition may be a transition to bring the signal levelback to the first signal level. As a consequence, it may be possible touse as the transition and the further transition transitions from thecommon first signal level to a common second signal level.

Additionally or alternatively, in a receiver a time resolution of thereceived oversampled signal may be better than the smallest distance ofthe plurality of expected positions.

This may allow the sampling circuit to reliably determine as to whetherthe transition falls into a predetermined range around an expectedposition.

Optionally, in a receiver, the time resolution may be better by at leasta factor of four than the smallest distance between the expectedpositions of the plurality of expected positions. This may allow thesampling circuit to reliably determine as to whether the position of thetransition falls into the predetermined range around an expectedposition.

Additionally or alternatively, in the receiver, the receiver circuit maybe configured to receive an initial sequence representing apredetermined calibration value. The sampling circuit may further beconfigured to determine the expected positions of the quantizationfunction based on the comparison of the calibration value and theinitial sequence. This may allow a more flexible transmission of datasince the time basis of a calibration function may be provided by thetransmitter intermittently, for instance regularly.

Optionally, in a receiver the initial sequence may comprise a firsttransition and a second transition, wherein the sampling circuit may beconfigured to determine the expected positions of the quantizationfunction based on a time between the first and second transitions of theinitial sequence and the calibration value. This may further allowproviding the time basis for the quantization function reliably based ona similar technique used for transmitting data.

Additionally or alternatively, in a receiver the receiver circuit may beconfigured to receive the signal asynchronously. This may allowsimplifying and implementing the receiver further since providing aclock signal to receive a time basis for the signal may be omitable.

A receiver may also be comprised in a transceiver, which furthercomprises a transmitter circuit configured generate a signal to betransmitted and/or to transmit the signal. The signal to be transmittedor transmitted may be a signal the receiver is configured to receive andprocess. However, the transmitter circuit may also use a differenttransmission protocol, a different transmission technique or acombination thereof. Hence, a transceiver may comprise a transmittercircuit along with a receiver as described before.

A receiver or a transceiver may be implemented as an integrated circuitcomprising a substrate into which the receiver is at least partiallyintegrated. The substrate may be a die or chip comprising a main surfaceand a thickness along a direction perpendicular to the main surface anda thickness along a direction perpendicular to the main surface, whereinthe thickness is smaller than the extension of the die along the mainsurface. For instance, the thickness may be at least a factor of 10smaller than a smallest extension of the substrate parallel to the mainsurface. The substrate may be a semiconductor substrate comprising asemiconducting material such as silicone (Si), gallium arsenide (GaAs)or similar materials.

The integrated circuit may be part of a discrete device. However, areceiver or a transceiver may also be implemented as a discrete devicecomprising not just a single substrate, die or chip, but may bedistributed over several substrates, dies or chips. The plurality ofsubstrates, dies or chips may be arranged or contained in a singlepackage. For instance, all parts of the discrete device may bemanufactured in a single process sequence such as a semiconductor waferprocess to fabricate the discrete device. Sometimes, parts of thediscrete device may be manufactured after a typical microelectronicwafer manufacturing process. In order not to pollute the waferfabrication, it may be possible to apply a final passivation layerprotecting the circuit and other elements before attaching larger,separate objects including, for instance, terminals of the discretedevice or the like.

Moreover, a discrete device may undergo a functional test before it isassembled into a more complex component or system. If such a task hasbeen carried out, the individual parts that went through this test maybe considered a discrete device. For instance, the test may comprise asimplified test procedure allowing to verifying if the discrete deviceworks and if it performs in the expected limits. For instance, the testmay be used to see if an additional calibration may be unnecessary,advisable or even necessary. For instance, to store additionalcalibration data, the discrete device may comprise storage locations tostore the calibration data.

A storage location may comprise one or more storage cells of the same orof different types. The storage cells may be implemented as volatile ornon-volatile storage cells. A non-volatile storage cell may be based onrandom access memory (RAM) technology, while a non-volatile storage cellmay be based, for instance, on electrically erasable and programmableread-only memory (EEPROM) technology, optical storage technology,magnetic storage technology or the like.

A method for receiving a signal comprises receiving a pulse widthencoded signal, determining a position of a transition of the pulse ofthe signal by oversampling the reference signal with respect to aquantization function, and generating a signal indicating an unexpectedevent, when the determined position of the transition deviates from anexpected position according to the quantization function by more than apredetermined range. The quantization function maps a plurality ofexpected positions to a plurality of values.

A program comprises a program code configured to perform such a method,when the program is executed on a programmable hardware. The program maybe stored on a machine-readable storage medium which includes theprogram code and which causes the machine to perform the method whenexecuted. The machine-readable storage medium may, for instance, includemachine-readable instructions, which, when executed, implement a methodor realize a receiver as described before. A programmable hardware may,for instance, comprise a processor, a central processing unit (CPU), agraphical processing unit (GPU), a field programmable gate array (FPGA),a system on chip (SOC) or any other form of programmable hardware. Theprogram may, for instance, comprise software or firmware, which may, forinstance, be stored in the previously-mentioned machine-readable storagemedium. Such a machine-readable storage medium may, for instance,comprise one or more memory locations as described before.

Mechanical components may be coupled to one another directly orindirectly via a further component. Electrical and other components canbe coupled to one another directly or indirectly in such a way thatinformation carrying or informing comprising signals can be interchangedor sent from one component to the other component. Moreover, electricaland other components can be electrically coupled directly or indirectlyto provide them with electrical energy, for instance, by providing asupply voltage and a supply current to the respective components.

Information carrying signals or information comprising signals can besent, provided or interchanged, for instance, using electrical, optical,magnetic or radio signals. The signals can be in terms of their valuesand their timely sequence independent from one another be discrete orcontinuous. For instance, the signals may be analog or digital signals.

BRIEF DESCRIPTION OF THE DRAWINGS

Several embodiments of the present invention will be described in theenclosed Figures.

FIG. 1 shows a simplified block diagram of a communication systemcomprising a receiver;

FIG. 2 shows a simplified diagram of a sequence of a signal toillustrate an operation if a receiver;

FIG. 3 shows a simplified sequence of a SPC- or SENT-based signal;

FIG. 4 illustrates a superposition of a signal with a distortion;

FIG. 5 shows a sequence of a signal to illustrate an operation of areceiver; and

FIG. 6 shows a flowchart of the method.

DETAILED DESCRIPTION

In the following, embodiments according to the present invention will bedescribed in more detail. In this context, summarizing reference signswill be used to describe several objects simultaneously or to describecommon features, dimensions, characteristics, or the like of theseobjects. The summarizing reference signs are based on their individualreference signs. Moreover, objects appearing in several embodiments orseveral figures, but which are identical or at least similar in terms ofat least some of their functions or structural features, will be denotedwith the same or similar reference signs. To avoid unnecessaryrepetitions, parts of the description referring to such objects alsorelate to the corresponding objects of the different embodiments or thedifferent figures, unless explicitly or—taking the context of thedescription and the figures into account—implicitly stated otherwise.Therefore, similar or related objects may be implemented with at leastsome identical or similar features, dimensions, and characteristics, butmay be also implemented with differing properties.

In many fields of technology, a demand exists to allow components of asystem to transmit data from one component to another using, forinstance, a digital transmission scheme. Sometimes, the communication isnot uni-directional but bi-directional allowing an exchange of data,commands, status information or the like. In the following description,information to be transmitted from one component to another componentwill be referred to as data irrespective of their content or theirmeaning. For instance, in the following description, status information,commands as well as other values or data will be referred to as data.

In these applications often very different design goals have to be takeninto consideration. However, in many cases a robust transmission of datawith respect to distortions, a simple implementation allowing and yet ahigh bandwidth for transmitting data represent important design goals.As a consequence, in many fields of technology, a demand exists toimprove a trade-off between these parameters.

Examples come, for instance, from high-volume and/or low-costimplementations, in which technically simple and, hence, cost-efficientsolutions may be important. For instance, in the field of components foran intra-vehicle communication, the individual components are oftensubjected to significant distortions and operating under difficultenvironmental influences including large variations of temperature,moisture and mechanical vibrations. For instance, electromagnetic burstsmay couple into electrical or electronic communication systems caused,for instance, by ignition systems, power control systems, or the like.

However, even under those more difficult operational conditions,components are often required to operate reliably and to be able totransmit and/or to receive data at a sufficiently high rate. In the caseof vehicle-related systems, this may be important, for instance, forsafety-related systems and components, which may directly or indirectlyinfluence the passengers' or the vehicle's safety. An example comes fromthe field of sensors and sensor-related applications. For instance, inthe case of a motorized vehicle, sensors may be used to monitorrotational angles, angular velocities or other parameters.

Due to the number of different sensors comprised in a car, a motorcycle,a truck or a similar vehicle, the sensors as well as their control unitsare subjected to corresponding cost pressure, favoring technically moresimple solutions, which should provide the possibility of a sufficientlyhigh bandwidth as well as a robust transmission of data. By providing abus system or a communication system with a sufficiently high bandwidth,it may be possible to reduce a total number of bus systems orcommunication systems by coupling more components to a single bus orcommunication system.

Although in the example described above, a vehicle-related applicationscenario has been described, in other fields of technology similarchallenges exist, which lead to similar demands. Therefore, without aloss of generality, in the following reference will be made to avehicle-related application, although similar examples may equally wellbe employed in other fields of applications and other fields oftechnology.

In the following a transmission technology will be described which isbased mostly on using electrical signals to transmit data. For instance,data may be encoded in an electrical voltage and/or an electricalcurrent being modulated or changed to transmit the data. For instance,in the protocols described below, a datum or piece of information istransmitted or received, which may comprise in principal any number ofdifferent states. However, in the following a bit-based transmissionprotocol will be considered more closely, in which an individual datummay comprise a specified number of bits, which translates into acorresponding number of different states. For instance, in the case of anibble-based protocol, each datum comprises 4 bits so that 16 (=2⁴)different states may be transmitted. In other fields of application, thenumber of bits may vary. Moreover, it is by far not required toimplement a bit-based transmission scheme. In principle, any number ofstates instead of the power of 2 (2^(n), n being an integer) may beused.

Examples of corresponding protocols comprise, for instance, SPC (shortPWM codes; PWM=pulse width modulation) or SENT (single-edge nibbletransmission). Both protocols are based on a PWM encoding scheme fortransmitting nibbles or multiples of nibbles. Each of the nibblescomprises exactly 4 bits.

In the following examples, the information or data to be transmitted isencoded in falling edges. In other examples, rising edges or anycombination of rising and falling edges may be used to encode data.

As outlined before, instead of electrical electronic transmissionschemes, also other transmission schemes including, for instance,optical transmission schemes, magnetic transmission schemes or wirelesstransmission schemes may be used to transmit or receive data.

FIG. 1 shows a simplified block diagram of a communication system 100comprising a receiver 110 and a transmitter 120. The transmitter 120 andthe receiver 110 are coupled to one another via a communication link130, which may be specifically designed to transmit data from thetransmitter 120 in a form generated by the transmitter 120 to thereceiver 110. The communication link 130 may be, for instance,configured to transmit electrical signals, although in other examplesthe communication link 130 may equally well be specifically designed totransmit optical signals, magnetic signals or other signals.

In some examples, the communication link 130 may eventually be replacedby a wireless communication link employing, for instance, a radio-basedtransmission scheme. Moreover, the transmission link 130 may be amagnetic communication link.

In the case of an electrical transmission scheme, the communication link130 may comprise one or more electrically-conductive lines or wires.These conductive lines or wires may, for instance, form an electricalbus to transmit data serially or in parallel. In other examples, thecommunication link 130 may comprise one or more optical fibers totransmit optical signals from the transmitter 120 to the receiver 110.

The receiver 110 comprises a receiver circuit 140, which is designed toreceive a pulse width encoded signal, and a sampling circuit 150, whichis coupled to the receiver circuit 140 and designed to determine aposition of a transition of a pulse of the signal by oversampling thereceived signal with respect to a quantization function. Thequantization functions maps a plurality of expected positions to aplurality of values. As will be laid out in more detail below, thesampling circuit 150 may generate a signal indicating an unexpectedevent, when the determined position of the transition deviates from anexpected position according to the quantization function by more than apredetermined range. The signal indicating the unexpected event may, forinstance, be accessible to other parts at an output 160. Depending onthe implementation, the output 160 may comprise an electrical signalline to provide the signal indicating the unexpected event as anelectrical signal or in any other form. For instance, the signalindicating the unexpected event may also be an optical signal, such thatthe output 160 may comprise, for instance, a light source such as alight-emitting diode (LED), a semiconductor laser or the like.Similarly, the output 160 may be designed to generate or provide amagnetic signal. In this case, the output 160 may, for instance,comprise a magnetic coil or the like.

In case of a processor-based implementation, the output 160 may comprisea storage location, in which at least one bit can be stored at leasttemporarily. A storage location may, for instance, comprise any suitablevolatile or non-volatile storage cell as discussed before.

The receiver circuit 140 may, for instance, be specifically designed tophysically receive signal transported via the communication link 130.The receiver circuit 140 may, for instance, comprise filters, amplifiersor other corresponding analog and/or digital circuits.

Before further details concerning the receiver 110 will be described incontext with the schematic representation or diagram of a signal, whichthe receiver 110 is capable of processing, it should be noted that thereceiver 110 may also be part of a larger component such as, forinstance, a transceiver 170. The transceiver 170 may comprise atransmitter circuit 180, which is also coupled to the communication link130 and designed to generate a signal to be sent over the communicationlink 130. To couple both the receiver 110 and the transmitter circuit180 to the communication link 130, an optional switch 190 or a similarmultiplexer or coupler may be implemented to allow both the receiver 110and the transmitter circuit 180 to access the communication link 130alternately or simultaneously.

The transmitter circuit 180 may be designed to generate a signal similarto the one the receiver 110 may receive, but may also generate a signaldifferent from the signal to be received by the receiver 110. Forinstance, a transmitter circuit 180 may use a different transmissionprotocol and/or a different transmission technology. As a consequence,the communication link 130 may be designed to transmit signals based ondifferent transmission protocols or the like. In another example, thetransceiver 170 may be coupled to a different communication link 130which is, however, not shown in FIG. 1 for the sake of simplicity only.This additional communication link would be an optional component, whichmay render the optional switch omitable.

FIG. 2 shows a schematic diagram of a signal which the receiver 110 canreceive and process. The signal is, to be more precise, a pulse widthencoded signal comprising a pulse 200 with a transition 210 on the basisof which the sampling circuit 150 is capable of obtaining a receivedvalue of a plurality of values by comparing the position of thetransition 210 with a corresponding plurality of expected positions. Thequantization function maps each of the expected positions to one valueof the plurality of values. For instance, the sampling circuit 150 maydetermine by oversampling the received signal a position of a transition210 and compare the position of the transition 210 to the expectedpositions according to the quantization function. For instance, on basisof the expected transition having the smallest distance to the positionof the transition 210 the sampling circuit 150 may determine the valueencoded in the signal using the quantization function. This value may bereferred to as the received value.

To explain this a little further, FIG. 2 comprises a plurality ofexpected positions 220-1, 220-2 and 220-3. A distance of a position of atransition 210 from the expected position 220-2 is smaller than adistance of a position of the transition 210 from the expected position220-1 as well as from the expected position 220-3. Therefore, based on aquantization function, mapping to the three expected positions 220depicted in FIG. 2 three values, the received value may be the oneassociated by the quantization function to the expected position 220-2.The values attributed to the expected positions may be different fromone another.

However, the signal may be subjected to distortions as will be outlinedin more detail in the context of FIG. 4. Therefore, the intendedposition of a transition 210 may be superimposed by such a distortionleading to a shift of the position of the transition 210. Due to theinterference of that distortion, it may happen that the transmittedsignal may be altered in terms of the value to be transmitted by thedistortion.

To be able to detect such a situation, the sampling circuit 150 comparesthe position of the transition 210 not only to the expected positions220 but also verifies as to whether the determined position of thetransition 210 deviates from the expected positions 220 corresponding tothe received value by more than a predetermined range 230. In FIG. 2predetermined ranges 230-1, 230-2 and 230-3 corresponding to theexpected positions 220-1, 220-2 and 220-3, respectively, are shown bydotted lines. In the example depicted in FIG. 2, the position of thetransition 210 falls well within the predetermined range 230-2 of theexpected position 220-2. As a consequence, the sampling circuit maydetermine the value corresponding to the expected position 220-2 as thereceived value.

In case, however, the transition 210 would deviate from the expectedposition 220 according to the quantization function by more than thecorresponding predetermined range 230, the sampling circuit 150 maygenerate the previously-mentioned signal indicating the unexpectedevent.

The sampling circuit 150 uses an oversampling technique for the receivedsignal to verify as to whether the position of the transition 210 fallswithin the predetermined range 230 of the corresponding expectedposition 220. For instance, the sampling circuit may operate at anoperational frequency being higher than a frequency corresponding to adistance between the expected positions 220. In other words, a timeresolution of the received oversampled signal may be better than asmallest distance of the plurality of the expected positions 220. Bothdetermining the relevant expected position 220 having, for instance, thesmallest distant from the position of the transition 210 as well as thequestion as to whether the position of the transition 210 falls in thepredetermined range 230 may then, for instance, be determined byemploying a counter. For instance, to enable the sampling circuit 150 toverify as to whether the position of the transition 210 deviates fromthe expected positions 220 by more than the corresponding predeterminedrange 230, the time resolution may be chosen to be better by at least afactor of 4 than the smallest distance between the expected positions220 of a plurality of expected positions. In other examples, thecorresponding factor may be higher, for instance, at least a factor of6, at least a factor of 8 or at least a factor of 10.

Based on the time resolution used for oversampling the received signal,the size of the predetermined regions 230 may be determined. Forinstance, the predetermined range may correspond to at the most 30%, atthe most 20% or to at the most 10% of a distance between two neighboringexpected positions 220.

In an implementation, in which the sampling circuit 150 uses a counterto determine as to whether the position of the transition 210 fallswithin the predetermined region 230 around the corresponding expectedposition 220, the predetermined range may, for instance, be given by apredefined number of samples according to a sampling time resolution ofthe received oversampled signal. Moreover, to simplify theimplementation of the receiver 110 even further, it may be possible toimplement the sampling circuit 150 such that the predetermined ranges230 for the expected position 220 of the plurality of expected positions220 are equally sized.

However, in other examples, the predetermined ranges 230 are at theexpected positions 220 may also be based on a predefined fraction of thevalues corresponding to the respective expected positions 220 accordingto the quantization function. For instance, the predefined fraction maybe 30%, 20% or 10% to give just some examples. The fraction maygenerally speaking be smaller than 50% in the case of a symmetricarrangement of the predetermined ranges 230 with respect to the expectedpositions 220. However, in other examples, the expected positions 220are by far not required to be in the center or midpoint of thepredetermined ranges 230.

In terms of the quantization function and the expected positions 220 onthe basis of which the quantization function maps the values to thecorresponding expected positions 220, the distances between neighboringexpected positions 220 according to the quantization functions may beequal. Such an example is depicted in FIG. 2, where the distancesbetween the expected positions 220-1, 220-2 is equal to the distancebetween the expected positions 220-2 and 220-3.

The quantization function assigning or attributing to each of theexpected positions 220 a value or a plurality of values may be monotone.For instance, the quantization function may be monotonically ormonotonically increasing. In the first case, the quantization functionmay, for instance, map the plurality of expected positions 220 arrangedin an ascending order to the plurality of values in an ascending order.In the latter case, the situation may be reversed. Here the quantizationfunction may map the plurality of expected positions 220 when beingarranged in an ascending order to the plurality of values arranged in adescending order. The values mapped by the quantization function may,for instance, be integer values. A maximum difference betweenneighboring integer values may be one, when the plurality of integervalues is arranged in an ascending order. For instance, the firstexpected position 220-1 may be mapped to an integer j, the secondexpected position 220-2 to the integer (j+1), the third expectedposition 220-3 to the integer (j+2) and so on. In other words, thequantization function may map to the expected positions 220 arranged inthe ascending order integer values being one smaller or larger than thepreceding value mapped to the preceding expected position 220.

Although in FIG. 2 a quantization function mapping three expectedpositions 220-1, 220-2 and 220-3 to three values is implicitly shown,the quantization function and the sampling circuit 150 may be designedto map any number of expected positions 220 to corresponding values. Inother words, the quantization function may have less expected positions220, but also a larger number of expected positions. The number ofexpected positions 220 may, for instance, correspond to the number ofstates a single datum can acquire. In the case of a single bit to betransmitted, a quantization function comprising only two differentstates, and hence two different expected positions 220, may suffice. Onthe other hand, when a nibble with its 4 bits is to be transmitted, inprinciple 16 different states and, hence, 16 different expectedpositions 220 should be mapped to the different values. In the case of 6bits, the number of expected positions climbs to 64 (=2⁶) and in thecase of a byte with 8 bits, the number of expected positions may rise upto 256 (=2⁸) different expected positions 220.

However, as outlined before, it is by far not necessary to use abit-based transmission scheme. In the case of a bit-based transmissionscheme with a datum comprising n bits, the number of expected positions220 may, for instance, comprise 2^(n) different expected positions 220.However, any other number may also be used in the framework ofquantization functions.

The receiver 110 and, for instance, its sampling circuit 150 may beconfigured to receive the signal comprising a further transition 240,which is located before the transition 210.

The value to be transmitted may then be encoded in a time period 250between the further transition 240 and the transition 210. Although thetransition 210 as well as a further transition 240 may be in principlebe transitions in different directions, a more reliable transmission ofdata may eventually be achievable when using for the transition 210 aswell as the further transition 240 transitions in a common firstdirection. As a consequence, it may be possible to reduce an impact oreven eliminate an impact of symmetries caused by the transmitter 120 forrising edges and falling edges. However, it should be noted that in FIG.2 the form and duration of the rising or falling edges has beenneglected for the sake of simplicity only.

To allow the transition 210 as well as a further transition 240 to betransitions in the common first direction, and to use only two signallevels, the receiver 110 may be designed to receive the signal furthercomprising an intermediate transition 260 in an opposite seconddirection. The intermediate transition 260 may then be positionedbetween the further transition 240 and the transition 210. As aconsequence, it may be possible to implement the transmitter 120 as wellas the receiver 110 such that the transitions 210, 240 and 260 eachcause the signal to change between a first and second signal level.However, the transition 210 as well as the further transition 240 aredirected in an opposite direction compared to the intermediatetransition 260.

The quantization function may, for instance, map the correspondingvalues to the expected positions 220 by subtracting an offset from thetime period 250 between the further transition 240 and the transition210. Depending on the implementation, the offset may be fixed orchangeable, for instance programmable.

As a precautionary measure, the receiver 110 may, for instance, discardor disregard a message comprising a received value, when the samplingcircuit 150 has generated the signal indicating an unexpected eventduring the reception of the message. The presence of the signalindicating the unexpected event may, for instance, be interpreted as anincreased probability that a distortion has interfered with atransmission so that the value received and decoded by the samplingcircuit 150 may have been distorted. In this case, it may be safer todisregard or discard the complete message instead of operating thesystem comprising the receiver based on the value which may have beendistorted.

A receiver 110 may be capable of operating and, hence, receiving thesignal asynchronously. This may allow the designer of a systemcomprising such a receiver to omit providing the receiver 110 with aclock signal for clocking purposes. Instead, a common time basis of thetransmitter 120 and the receiver 100 may be shared differently. Forinstance, the receiver 110 may be configured to receive an initialsequence to 270 representing a predetermined calibration value. Thesampling circuit 150 may then be designed to determine the expectedpositions 220 based on a comparison of the calibration value and theinitial sequence 270. For instance, the initial sequence 270 maycomprise a first transition 280 and a second transition 290 followingthe first transition. A time 300 between the first and secondtransitions 280, 290 may then be used as a time basis to determine theexpected positions 220. For instance, a time unit or tick may be definedby dividing the calibration value by the time 300. The calibration valuemay be fixed or changeable, for instance programmable, depending on theimplementation and standard according to which a receiver 110 operates.

Once again, the first and second transitions 280, 290 may share the samedirection. As a consequence, a third transition 310 may be arranged inbetween the first and second transitions 280, 290. Once again, the threetransitions 280, 290 and 310 may be transitions between the previouslymentioned first and second signal levels.

In the following, an example coming from the automotive sector will bedescribed in more detail. SPC and SENT use a parts modulation encodingfor the transmission of 4-bit nibbles. A receiver may install anadditional safety mechanism which may allow detecting faults due to aninfringement of a timing specification. In a standard SENT or SPCtransmission scheme N-bits cyclic redundancy check (CRC) values over allbits of a message are used. For instance, in the SENT standard, it isadditionally proposed to check for the nibble length only for thesynchronization pulse. Values of +/−1.5% may be used which is less thanthe resolution of this pulse, which in turn is +/− 1/56, whichcorresponds to +/−1.79%. A receiver 110 defines a range of fractionalnibble length measurements which are not accepted by the receiver 110.This may allow an implementation of a further safety measure on top oralternatively to the CRC value verification, which increases theprobability to detect transmission faults.

FIG. 3 shows an example of an encoding scheme for two 12 bit signals. Tobe more precise, FIG. 3 shows a schematic diagram of a signal having anoverall message length of 154 to 270 clock ticks depending on the valuesto be transmitted. A minimum nibble period may, for instance, correspondto 36 μs at a length of 3 μs per clock tick. This corresponds to aminimum nibble length of 12 ticks (36 μs=12 ticks·3 μs/tick). A nibbleencoded period of time may, for instance, correspond to 36 μs plusj-times 3 μs, where j is an integer in the range from 0 to 15(T_(nibble)=j·3 μs; j=0, . . . , 15). In other words, a quantizationfunction maps the expected positions, which are separated by one tickand which are equally spaced to the values 0 to 15 according to anascending order of the expected positions 220. The offset value used todetermine the received value by subtracting it from the time period 250is here 12 ticks or the previously mentioned 36 μs.

However, before the description of the schematic representation of FIG.3 is continued, it should be noted that this merely represents anexample. Other implementations and examples may have a higher or lowerfrequency corresponding to a higher or lower time per tick,respectively. Moreover, all other parameters including, for instance,the directions of the transitions, the calibration value, and the offsetmay be implemented differently.

The schematic diagram of FIG. 3, once again comprises an initialsequence 270 comprising a first transition 280, a second transition 290and a third transition 310 arranged in between the first and secondtransitions. The time 300 between the first and second transitions 280,290 corresponds to a calibration value of 56 ticks. Based on thiscalibration value, the time 300 results in a common time basis used bythe transmitter 120 generating the signal shown in FIG. 3 and thereceiver 110 receiving the signal. Using this common time basis allowsthe receiver 110 to decode the values comprised in the signal ormessage. In other words, the initial sequence 270 allows the signal tobe asynchronously transmitted.

A SENT standard defines its messages depending on the length of twoadjacent falling edges or transitions. In order to provide the timebasis that allows to decode the messages of a sensor or a similar devicethat have a time basis, which has a low precision and may depend ontemperature as well, the first pulse comprised in the initial sequence270 in every frame has a fixed length of 56 ticks. The time 300 of thisinitial pulse is measured by the receiver 110 and divided by the knownlength or calibration value of 56 to extract the actual tick length thatis generated by the transmitter 120 or the transmitting sensor. Theextracted tick length may then be used to decode the information of thefollowing nibbles.

The message as depicted in FIG. 3 comprises apart from the initialsequence 270 a plurality of packages 320-0, 320-1, . . . , 320-6 as wellas a check sum 330. The plurality of packages 320 comprises as aninitial package 320-1 a status and communication value which is encodedin the example depicted in FIG. 3 by a nibble comprising the previouslymentioned 4 bits. The initial package 320-0 comprises the value 0 sothat a time period 250 between the transition 210 and the furthertransition 240 corresponds to 12 ticks based on the time basisestablished by the initial sequence 270. It should be noted that in theexample depicted here the further transition 240 corresponds to thesecond transition 290 of the initial sequence 270. In between thetransition 210 and the further transition 240, the intermediatetransition 260 is arranged.

Similarly, the plurality of packages further comprises 6 packages 320-1,. . . , 320-6 each comprises 4 bits of data which are also encoded as asum of the offset value (12 ticks in the example here) added to theinteger value of the 4 bits·1 tick. For instance, the first package320-1 corresponds to a value of 50 so that a time period 250-1 betweenthe corresponding transition 210-1 and the corresponding furthertransition 240-1 has a length of 27 ticks. The length of the time period250-1 is the sum of the offset of 12 ticks plus the integer value of15·1 tick. It should be noted that the transition 210-0 of the initialpackage 320-0 and the further transition 240-1 of the first package320-1 correspond to one another. Similarly, in the example depicted thetransition 210-k of the package 320-k corresponds to the furthertransition 240-(k+1) of the following package 320-(k+1), where k is aninteger in the range between 1 and 5.

Similarly, the time period 250-2 corresponding to a value of 5 has alength of 17 ticks, the time period 250-3 of the third data package320-3 corresponding to a value of 10 has a length of 22 ticks, the timeperiod 250-4 of the fourth data package 320-4 has a length of 40 tickscorresponding to a value of 2, the time period 250-5 of the fifth datapackage 320-5 has a length of 20 ticks corresponding to a value of 8 andthe time period 250-6 of the sixth data package 320-6 has a length of 12ticks corresponding to a value of 0. The first three data packages320-1, 320-2, 320-3 may represent 12 bits of a first signal, while thedata packages 320-4, 320-5 and 320-6 correspond to 12 bits of a secondsignal.

The data packages 320 are followed by the check values 330 encoded in acorresponding time period 250′ having a length of 21 ticks correspondingto a value of 9. The check value 330 comprises in the example depictedhere also 4 bits and may, for instance, represent a CRC value of thedata packages 320-1, . . . , 320-6. The check value 330 may be followedby an optional pause pulse 340. The pause pulse may, for instance, havea length of 77 ticks as indicated in FIG. 3. In order to change themessage content in a way that it is not detectable by an infringement ofthe protocol, an interference has to appear in the proximity of one ofthe transitions 210, 240. In other words, to change a value of amessage, a distortion may have to appear approximately at a falling edgeof a protocol depicted in FIG. 3.

To illustrate this further, FIG. 4 shows the signal in the lower partrepresenting a message having a value of 2 (binary representation:0010), which equals based on the offset of 12 ticks to a time period 250of 14 bit times or ticks. The horizontal axis of FIG. 4 represents thetime axis in units of ticks. In the upper part of FIG. 4 distortions350-1, 350-2, 350-3 and 350-4 are depicted. Any distortion may have apositive or negative sign compared to the current signal levels. Thedistortions 350 depicted in FIG. 4 are spike-shaped.

The distortions 350-1 and 350-4 represent detectable distortions, whichlead to a violation of timing constraints imposed by the specificationof the respective SENT standard. For instance the first distortion 350-1would lead to a time period between a corresponding transition 210 andthe further transition 240 which is smaller than the offset value of 12ticks. Similarly, the distortion 350-4 would result in an additionaltransition which violates the SENT timing requirements.

However, the distortions 350-2 and 350-3 may lead to the transition 210being shifted by one tick to a lower value and a higher value,respectively. In other words, while the transition 210 as intended wouldcorrespond to a time period of 14 ticks, the distortion 350-2 may causethe time period 250 to be shortened to 13 bit times or ticks. Similarly,the distortion 350-3 may cause the time period 250 to increase by onetick. As a consequence, any of the distortions 350-2, 350-3 may lead toan alteration of the position of the transition 210 and, hence, to achange of the time period that translates into a change of the value.

In order to increase the probability that a shift of a transition 210,240 or—in the examples depicted here—of a falling edge infringes theprotocol, a receiver 110 introduces a range of prohibited fractions oftick times that are checked when the content of the value or nibble isdecoded.

FIG. 5 illustrates this in a similar situation as depicted in FIG. 4.However, the time period 250 between the further transition 240 and thetransition 210 corresponds here to a value of 9. Since in the examplesdepicted here the time periods 250 are taken between falling edges, thetime period 250 is also referred to as T_(f2f) (f2f=falling-to-falling).

FIG. 5 further depicts for the values 0, 9 and 15 the expected positions220-0, 220-9 and 220-15. For the two expected positions 220-9, 220-15also the predetermined ranges 230-9 and 230-15, respectively, have beenmarked by dotted lines in FIG. 5. Whenever the transition 210 falls intothe corresponding predetermined range 230-9, the encoded value mayconsidered unaltered. If, however, the transition 210 should fall intothe hashed region outside the predetermined ranges 230, the signalindicating the unexpected event may be generated by the sampling circuit150 and, for instance, the message may be discarded or disregarded.

The predetermined ranges 230 may, for instance, correspond to atolerance range of for instance +/−10% of the corresponding value. Inother words, the predetermined range 230-9 may correspond to a value of8.91 to 9.09 ticks or rounded to a value between 8.9 and 9.1 ticks. Ifthe position of the transition 210 as determined by the sampling circuit150 should fall outside the predetermined range 230-9 as mentioned, thesignal indicating the unexpected event may be generated. Similarly, thepredetermined range 230-15 for the expected position 220-15corresponding to the value of 15 may comprise the values from 14.85 to15.15 corresponding to 10% of the value mapped to the expected position220-1 by the quantization function. In other examples a different schememay equally well be employed. For instance, the predetermined ranges 230may be given by an absolute tick time. For instance, in the case of anabsolute tick time of +/−0.1 tick times, the predetermined ranges 230would be equally wide. For instance, the predetermined range 230-9correspond in this case to values between 8.9 and 9.1, while thepredetermined range 230-15 corresponding to the expected position 220-15comprises the values 14.9 to 15.1. In other examples, also otherpredetermined ranges 230 may be used, which may, for instance, use thetime period 250 (for instance Tf2f) as a basis to define thepredetermined ranges 230.

This principle can be implemented, for instance, by introducing acertain granularity of a sampling rate of the receiver 110. This may,for instance, be done by a peripheral clock of a capture and compareunit and a checking for certain limits of the received counts from afalling to a falling edge or similar transitions. For instance, such acheck mechanism may be implemented similar to the check of thesynchronization pulse of the initial sequence 270.

When, for instance, assuming a tick time of 1.5 μs, a peripheral clockof a central control unit of 6.7 MHz may provide already a samplingwithin a 10% tolerance of 1 clock tick. Doubling the sample rate mayallow already a decision window of +/− two of the least significant bitsof the value provided by the central control unit to decide if the edgeis within the required predetermined range 230, which is also referredto as window.

If not, the whole packet or message can either be skipped or at least awarning for possible degradation of the reception can be flagged on thereceiver side. On top of the above-described timing check, the variationof the timing may be checked by the following measures. For instance,the timing of the sensors or other transmitters 120 may be caused mainlydue to temperature variations and aging drift. An error that appears atthe falling edge of the initial 56 tick synchronization pulses of theinitial sequence 270 may be detected, for instance, by comparison of thelength of a neighboring synchronization pulse of a previous initialsequence 270 to be equal with a limited tolerance T_synctol, which canbe much smaller than the proposed value of +/−1.5% according to the SENTstandard. Additionally or alternatively, the actual synchronizationpulse of the initial sequence 270 may be checked with respect to anaverage or by using an infinite impulse response filter monitoring alength of the preceding synchronization pulses. This may give a betterlong-term check than just checking neighboring or adjacent pulses.However, this may require the receiver to receive more initial sequences270.

Moreover, the receiver 110 may calibrate on synchronization as well ason its decision. In this scenario 110, which may for instance be part ofa central control unit, may receive information concerning such an edgedpoint by applying any kind of low-pass filtering including, forinstance, a running average filter, or more complex infinite impulseresponse filters, finite impulse response filters, minimum or maximumtrackers or the like. Moreover, it may be possible to send well-definedinitialization messages after a power up to allow a calibration of thetimings and to have a time basis for the later transmissions.

To allow the receiver 110 to operate with a corresponding transmitter120 it may be advisable to specify the required safety features andprotocols.

Using a receiver 110 may allow verifying the message integrity withoutextending the length of the check sum on each message. This may infringethe data rate requirements, especially on low data rate sensor buses andmay furthermore jeopardize upwards compatibility with existingstandards.

As a consequence, a receiver 110 may be used in the framework of an SPCsensor interface, which may provide an improved safety level by acorresponding timing evaluation.

FIG. 6 finally shows a flowchart of a method comprising in a processP100 receiving a pulse width encoded signal. In a process P110 aposition of a transition 210 of the pulse 200 is determined byoversampling the received signal with respect to a quantizationfunction. In a process P120 a signal indicating an unexpected event isgenerated, when the determined position of the transition 210 deviatesfrom an expected position 220 according to the quantization function bymore than a predetermined range 230. The quantization function maps theplurality of expected positions 220 to a plurality of values.

Although in FIG. 6 a specific order of the processes P100, P110 and P120is shown, the individual processes are by far not required to beexecuted in the order as given in FIG. 6. The order of the processes maybe changed arbitrarily. Moreover, the processes may be performed timelyoverlapping or even simultaneously. Moreover, the processes may beexecuted or performed in a loop. The loop may be interrupted, when apredefined condition is fulfilled.

The description and drawings merely illustrate the principles of theinvention. It will thus be appreciated that those skilled in the artwill be able to devise various arrangements that, although notexplicitly described or shown herein, embody the principles of theinvention and are included within its spirit and scope. Furthermore, allexamples recited herein are principally intended expressly to be onlyfor pedagogical purposes to aid the reader in understanding theprinciples of the invention and the concepts contributed by theinventor(s) to furthering the art, and are to be construed as beingwithout limitation to such specifically recited examples and conditions.Moreover, all statements herein reciting principles, aspects, andembodiments of the invention, as well as specific examples thereof, areintended to encompass equivalents thereof.

Functional blocks denoted as “means for . . . ” (performing a certainfunction) shall be understood as functional blocks comprising circuitrythat is adapted for performing or to perform a certain function,respectively. Hence, a “means for s.th.” may as well be understood as a“means being adapted or suited for s.th.”. A means being adapted forperforming a certain function does, hence, not imply that such meansnecessarily is performing said function (at a given time instant).

The methods described herein may be implemented as software, forinstance, as a computer program. The sub-processes may be performed bysuch a program by, for instance, writing into a memory location.Similarly, reading or receiving data may be performed by reading fromthe same or another memory location. A memory location may be a registeror another memory of an appropriate hardware. The functions of thevarious elements shown in the Figures, including any functional blockslabeled as “means”, “means for forming”, “means for determining” etc.,may be provided through the use of dedicated hardware, such as “aformer”, “a determiner”, etc. as well as hardware capable of executingsoftware in association with appropriate software. When provided by aprocessor, the functions may be provided by a single dedicatedprocessor, by a single shared processor, or by a plurality of individualprocessors, some of which may be shared. Moreover, explicit use of theterm “processor” or “controller” should not be construed to referexclusively to hardware capable of executing software, and mayimplicitly include, without limitation, digital signal processor (DSP)hardware, network processor, application specific integrated circuit(ASIC), field programmable gate array (FPGA), read only memory (ROM) forstoring software, random access memory (RAM), and non-volatile storage.Other hardware, conventional and/or custom, may also be included.Similarly, any switches shown in the Figures are conceptual only. Theirfunction may be carried out through the operation of program logic,through dedicated logic, through the interaction of program control anddedicated logic, the particular technique being selectable by theimplementer as more specifically understood from the context.

It should be appreciated by those skilled in the art that any blockdiagrams herein represent conceptual views of illustrative circuitryembodying the principles of the invention. Similarly, it will beappreciated that any flow charts, flow diagrams, state transitiondiagrams, pseudo code, and the like represent various processes, whichmay be substantially represented in computer readable medium and soexecuted by a computer or processor, whether or not such computer orprocessor is explicitly shown.

Furthermore, the following claims are hereby incorporated into theDetailed Description, where each claim may stand on its own as aseparate embodiment. While each claim may stand on its own as a separateembodiment, it is to be noted that—although a dependent claim may referin the claims to a specific combination with one or more otherclaims—other embodiments may also include a combination of the dependentclaim with the subject matter of each other dependent claim. Suchcombinations are proposed herein unless it is stated that a specificcombination is not intended. Furthermore, it is intended to include alsofeatures of a claim to any other independent claim even if this claim isnot directly made dependent to the independent claim.

It is further to be noted that methods disclosed in the specification orin the claims may be implemented by a device having means for performingeach of the respective processes of these methods.

Further, it is to be understood that the disclosure of multipleprocesses or functions disclosed in the specification or claims may notbe construed as to be within the specific order. Therefore, thedisclosure of multiple processes or functions will not limit these to aparticular order unless such processes or functions are notinterchangeable for technical reasons.

Furthermore, in some embodiments a single process may include or may bebroken into multiple sub-processes. Such sub-processes may be includedand part of the disclosure of this single process unless explicitlyexcluded.

What is claimed is:
 1. A receiver comprising: a receiver circuit toreceive a pulse width encoded signal; and a sampling circuit to:determine a position of a transition of a pulse of the pulse widthencoded signal by oversampling the pulse width encoded signal withrespect to a quantization function, and generate a signal, indicating anunexpected event, when the determined position of the transitiondeviates from an expected position according to the quantizationfunction by more than a predetermined range, the quantization functionmapping a plurality of expected positions to a plurality of values. 2.The receiver according to claim 1, wherein the sampling circuit isconfigured to: determine a received value, of the plurality of values,based on the quantization function and an expected position,corresponding to the received value, when the determined position of thetransition falls within the predetermined range around the expectedposition corresponding to the received value.
 3. The receiver accordingto claim 1, wherein the receiver circuit is configured to: disregard amessage, comprising a received value, of the plurality of values, whenthe sampling circuit has generated the signal indicating the unexpectedevent.
 4. The receiver according to claim 1, wherein the predeterminedrange corresponds to at most 30% of a distance between two neighboringexpected positions.
 5. The receiver according to claim 1, wherein thepredetermined range around the expected position is given by apredefined number of samples according to a sampling time resolution ofthe oversampled pulse width encoded signal.
 6. The receiver according toclaim 1, wherein predetermined ranges for expected positions, of theplurality of expected positions, are equally sized.
 7. The receiveraccording to claim 1, wherein the predetermined range around theexpected position, of the plurality of expected positions, is based on apredefined fraction of a value, of the plurality of values correspondingto the expected position, and according to the quantization function. 8.The receiver according to claim 1, wherein distances between neighboringexpected positions, according to the quantization function, are equal.9. The receiver according to claim 1, wherein the quantization functionis monotone.
 10. The receiver according to claim 1, wherein thequantization function maps the plurality of expected positions to aplurality of integer values.
 11. The receiver according to claim 10,wherein a maximum difference between neighboring integer values, of theplurality of integer values, is one when the plurality of integer valuesare arranged in an ascending order.
 12. The receiver according to claim1, where the pulse width encoded signal includes: a value, of theplurality of values, encoded in a time period between a furthertransition and the transition, the further transition occurring beforethe transition.
 13. The receiver according to claim 12, wherein thequantization function maps the position of the transition to the value,of the plurality of values, by subtracting a predefined offset from thetime period between the further transition and the transition.
 14. Thereceiver according to claim 12, wherein the pulse width encoded signalincludes the further transition and the transition as transitions in acommon first direction.
 15. The receiver according to claim 14, whereinthe pulse width encoded signal includes an intermediate transition in anopposite second direction, the intermediate transition being positionedbetween the further transition and the transition.
 16. The receiveraccording to claim 1, wherein a time resolution of the oversampled pulsewidth encoded signal is better than a smallest distance between expectedpositions of the plurality of expected positions.
 17. The receiveraccording to claim 16, wherein the time resolution is better by at leasta factor of four than the smallest distance between expected positionsof the plurality of expected positions.
 18. The receiver according toclaim 1, wherein the receiver circuit is configured to: receive aninitial sequence representing a predetermined calibration value, andwherein the sampling circuit is further configured to: determineexpected positions, of the plurality of expected positions of thequantization function, based on a comparison of the predeterminedcalibration value and the initial sequence.
 19. The receiver accordingto claim 18, wherein the initial sequence comprises a first transitionand a second transition, and wherein the sampling circuit is configuredto: determine the expected positions, of the plurality of expectedpositions, of the quantization function based on a time between thefirst and second transitions of the initial sequence and the calibrationvalue.
 20. The receiver according to claim 1, wherein the receivercircuit is configured to receive the pulse width encoded signalasynchronously.
 21. A method, comprising: receiving a pulse widthencoded signal; determining, by a sampling circuit, a position of atransition of a pulse of the pulse width encoded signal by oversamplingthe pulse width encoded signal with respect to a quantization function;and generating, by the sampling circuit, a signal, indicating anunexpected event, when the determined position of the transitiondeviates from an expected position according to the quantizationfunction by more than a predetermined range, the quantization functionmapping a plurality of expected positions to a plurality of values. 22.A non-transitory computer-readable medium storing instructions, theinstructions comprising: a plurality of instructions, which whenexecuted by programmable hardware, cause the programmable hardware to:receive a pulse width encoded signal; determine a position of atransition of a pulse of the pulse width encoded signal by oversamplingthe pulse width encoded signal with respect to a quantization function;and generate a signal, indicating an unexpected event, when thedetermined position of the transition deviates from an expected positionaccording to the quantization function by more than a predeterminedrange, the quantization function mapping a plurality of expectedpositions to a plurality of values.